Huddersfield Town rejected a
"It was a huge offer and, rightly so, because Karlan is a top, top player who will go on to grace the Premier League in years to come - I have no doubt about that," Cowley told the Huddersfield Examiner.
"We have to thank the chairman - luckily he is a supporter first and chairman second. I don't think his bank manager was very pleased, but we were!"
And although the 22-year-old didn't register at Craven Cottage, the Terriers boss knows just how vital his leading scorer will be, if his side is to remain in the division past the end of the season.
Not only that, Cowley was full of praise for the attacking star's desire to remain at the John Smith's Stadium in spite of Premier League interest.
"I thought it was a really intelligent decision because firstly Karlan had to want to stay, which he does and which is very important," said Cowley. "Let's be fair to the kid, there was a lot of interest from a lot of clubs who would pay him an awful lot of money, so credit to him that he was willing to stay and wanted to stay.
"Credit to the club, too, for staying strong, because we need our best players in this difficult moment, and it's great we've been able to keep them."
Huddersfield signed Grant from Charlton 12 months ago in a bid to improve their chances of Premier League survival.
However, despite the forward's four goals in 13 games, Grant's best efforts were not enough to stop the club slipping into the lower tier.
A year down the line, the Terriers are trying to hold onto their Championship status but with a player of Grant's calibre on their books, they have more than a fighting chance.